Determination of Benzoic Acid in Packed Fruit Juice and Soft Drink Samples by UV-Vis Spectrophotometry and Titration Methods

Abstract

Benzoic acid is one of the most commonly used food preservatives. The use of these preservatives in food products, however, should be monitor in order to assure their safe dose for not exceed the limit stated by regulatory body. Therefore, it is important to assess the amount of benzoic acid in soft drinks by cost effective and simple method for frequent monitoring. The objective of this work was to extract and investigate the concentrations of benzoic acid present in fruit juices and soft drinks by UV-Vis spectrophotometric and titrimetric method. A total of 39 samples were collected from Jimma market. To find the best extraction condition different parameters such as extraction solvent, volume and stability were assessed and optimized. Benzoic acid residues obtained from the sample by optimized extraction condition were dissolved in 10 mL of methanol and detected at 225 nm. The level of Benzoic acid in fruit juice and Soft drink samples by using UV-Vis spectrometry were in the range of 81.5 ± 0.1 – 385.0 ± 0.1 and 284.0 ± 0.07– 400.9 ± 0.4 respectively. While the level of Benzoic acid in fruit juice and Soft drink by using titration were in the range of 139.0 ± 0.1 – 182.5 ± 1.0 and 215.0 ± 0.4 – 221.0 ±0.2 respectively. The linearity and r 2 for UV-Vis method was 1-10 ppm and r2 0.996 respectively. The limit of detection (LOD) and the limit of quantification (LOQ) of benzoic acid was 0.16 ppm and 0.47 ppm by the UV-Vis method, while the method of titration was 0.58 ppm and 1.92 ppm respectively. The two-method demonstrated good accuracy with % recovery ranges 94.89-104 % for the UV-Vis method and 80- 103% for the titration method. The percent relative standard deviation of UV-Vis method ranged from 0.18-1.35, for intra-day, and from 1.1-5.8 for inter-day variation. Benzoic acid levels in all of the samples tested within the maximum acceptable ranges for fruit juice and soft drinks (<1000 ppm), as indicated by the joint FAO/WHO Food Standards Program Codex Committee on Food Additives and Contaminants. But, for the imported samples the Benzoic acid were higher, which indicates that there should be monitoring of the level of preservatives for safe conception before distribution. At P<0.05 both methods show significance differences.